This invention relates to a life indicator for indicating the service life of equipment whose service life is determined on the basis of a total water flow and a cartridge for a water purifier or a demineralizer equipped with this life indicator.
In recent years, in towns and cities, water quality has been contaminated due to an increase in population and industrial development, so that offensive odors and deterioration of taste of city water have become a public problem. For this reason, a household water purifier which is easily attached to a city water faucet to purify city water has been used widely. The water purifier is equipped with an exchangeable cartridge composed of a hollow fiber and activated carbon, and is adapted to remove offensive odors and various germs contained in city water by passing city water through the cartridge. The cartridge loses its function when the total water flow of city water passed through the cartridge exceeds specified quantity. That is, the a service life of the cartridge is determined on the basis of the above specified quantity and expires at a time when the total water flow reaches the above specified quantity. The cartridge generally exhausts its service life at about four to six months and must be exchanged.
Conventionally, a time at which a specified period has elapsed from the date the cartridge was placed into use written in the cartridge has been judged uniformly as the time to exchange the cartridge, and the cartridge has been exchanged.
However, the following problems have occurred in the above system based on writing the date of placing into use.
(1) The time to be exchanged is not clear when the user forgets to write the date of placing the unit in use, or the date becomes blurred.
(2) The quantity of water flow of city water through the cartridge differs for each household. Therefore, a cartridge which has not exhausted its service life yet but is functioning well might be exchanged, or a cartridge which has already exhausted its service life and is not functioning is still used successively, when the time to be exchanged is judged by an application period.
As a means for solving the above problems, an indicator using a float is well known. This indicator is one which utilizes a decrease in the quantity of water flow due to clogging of the hollow fiber in the cartridge, and can indicate a state of clogged hollow fiber to the outside by a mark attached to the float which sinks or rises on the basis of the decrease in the quantity of water flow. However, it sometimes occurs that the indicator indicates a wrong state because the quantity of water flow will be decreased when the water pressure is low or the faucet is partly closed. In addition, the service life of the cartridge can not be indicated correctly because only the state of the hollow fiber is indicated but the state of activated carbon is not indicated.
A cartridge equipped with a circuit for measuring an application time may be thought of, however, it is generally required to take countermeasures against changes in environment and external noises for an application as long as four to six months. Consequently, such a problem will arise that this indicator becomes complicated and expensive.
There is a demineralizer for obtaining water having a higher purity than that offered by the water purifier. The demineralizer is used for an industrial purpose in contrast with the water purifier generally used for domestic purpose. The demineralizer is also detachably equipped with a cartridge the service life of which is determined by the total water flow. This cartridge is equipped with an ion exchange resin. Exhaustion of the service life of the cartridge for a demineralizer has so far been detected as follows. (1) The service life is judged as exhausted when a specific resistance of purified water measured by a specific resistance meter becomes lower than a specified value, and (2) an indicator equipped with a circuit for measuring a water flowing time is installed because the demineralizer is one which can control a quantity of water flow per hour, and the total water flow is calculated by measuring the water flowing time by this indicator, so that the service life is judged as exhausted when the total water flow exceeds a specified quantity. However, there have been problems in the method (1) that the demineralizer itself has become expensive because of the expensive specific resistance meter, and in the method (2) that the demineralizer has become complicated and expensive as described above.